Improve diagnostic message when QIR codegen fails due to a runtime er…

…ror (#809)

This change includes the error string from runtime errors in the pop-up
error dialog when QIR generation fails.

<img alt="image"
src="https://github.com/microsoft/qsharp/assets/12157751/4784f746-01ef-45cb-acdb-19939a0cbc18">


Closes #747

vscode/src/qirGeneration.ts

@@ -73,7 +73,7 @@ export async function getQirForActiveWindow(): Promise<string> {
   } catch (e: any) {
     log.error("Codegen error. ", e.toString());
     throw new QirGenerationError(
-      "Code generation failed. Please ensure the code is compatible with the QIR base profile " +
+      `Code generation failed due to error: "${e.toString()}". Please ensure the code is compatible with the QIR base profile ` +
         "by setting the target QIR profile to 'base' and fixing any errors."
     );
   } finally {